Within five years, a woolly mammoth will likely be cloned, according to scientists who have just recovered well-preserved bone marrow in a mammoth thigh bone. Japan's Kyodo News first reported the find. You can see photos of the thigh bone at this Kyodo page. Russian scientist Semyon Grigoriev, acting director of the Sakha Republic's mammoth museum, and colleagues are now analyzing the marrow, which they extracted from the mammoth's femur, found in Siberian permafrost soil.

Mammoths used to be a common sight on the landscape of North America and Eurasia. One of my favorite papers of recent months concerned the earliest-known depiction of an animal from the Americas. It was a mammoth engraved on a mammoth bone. Many of our distant ancestors probably had regular face-to-face encounters with the elephant-like giants.

The key to cloning the woolly mammoth is to replace the nuclei of egg cells from an elephant with those extracted from the mammoth's bone marrow cells. Doing this, according to the researchers, can result in embryos with mammoth DNA. That's actually been known for a while.NEWS: Prehistoric Dog Found With Mammoth Bone in Mouth

What's been missing is woolly mammoth nuclei with undamaged genes. Scientists have been on a Holy Grail-type search for such pristine nuclei since the late 1990s. Now it sounds like the missing genes may have been found. In an odd twist, global warming may be responsible for the breakthrough. Warmer temperatures tied to global warming have thawed ground in eastern Russia that is almost always permanently frozen. As a result, researchers have found a fair number of well-preserved frozen mammoths there, including the one that yielded the bone marrow.

Is it such a good idea, however, to clone animals that have long been extinct? For a while there's been some discussion of a real-life Jurassic Park setup containing such animals. Introducing these beasts into existing ecosystems could be like bringing in a potentially invasive species that would try to fill some space presently held by other animal(s). Even if the cloned animals were contained in special parks, there could still be a risk of spreading. So if the woolly mammoth is successfully cloned sooner rather than later, we'd probably be left with more questions and controversy than answers, at least in the short term.